A fuel cell has a structure in which an electrolyte is sandwiched between two electrodes formed of porous metal or carbon. This structure is called a single cell. At an anode, hydrogen gas or another fuel is supplied from outside, approaches a reaction zone through pores in the electrode and is converted to active hydrogen atom by being adsorbed onto a catalyst in the electrode. As the hydrogen atom is to hydrogen ions, two electrons are drawn from the anode to a cathode on the opposite side through an external circuit, resulting in electric current. At the cathode, oxygen supplied from outside, the hydrogen ions delivered through the electrolyte and the electrons delivered through the external circuit react, producing water.
In a polymer electrolyte membrane fuel cell (PEMFC), a platinum catalyst is commonly used to facilitate a reaction whereby hydrogen gas is oxidized to produce hydrogen ions at the anode. For example, a supported catalyst with a surface entirely or partly coated with platinum and molybdenum carbide or tungsten carbide is disclosed. However, the high cost and limited supply of platinum are an obstacle to commercialization of fuel cells.
Therefore, in order to decrease the use of the platinum catalyst, a method of using a conductive carbon material with a large specific surface area as a support and loading platinum in fine particulate state on the support, thereby increasing the specific surface area of the platinum catalyst, is employed.
In this regard, nanotechnology and carbon structures are promising technologies in the cutting-edge research fields of the future. To synthesize metal nanoparticles and carbon structures having superior properties via a simple and economical method is a very important task in the field of catalyst engineering. Although various metal nanoparticle synthesis methods and carbon structure synthesis methods have been developed, these methods are problematic in that they require complicated processes, are costly and require the addition of additional chemicals. The additionally added substances are various acidic or basic materials, many of which are harmful to the human body and the environment. Such economic and environmental disadvantages are acting as an obstacle to the industrialization of nanoparticle catalysts supported on carbon supports.
Accordingly, research and development of an economical and environment-friendly method for preparing a high-performance metal nanoparticle catalyst supported on a carbon support are necessary.